how to add missing purchase b2b invoice of march 2018 in current month return of gstr 2

pls help me to to add my b2b purchase invoice of march 2018 in current month.

b2b invoice is wrongly entered by supplier in unregistered buyer.

but i have already taken ITC of that missing b2b in march 2018 gstr3b.

pls help how i can add that missing b2b purchase inv. in gstr2 in August 2018